Note: Descriptions are shown in the official language in which they were submitted.
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1 FIELD OF INVENTION
This is a divisional application of application serial number 336,801.
BACKGROUND OF THE INVENTION
. . .
Fire detector devices may be designed to actuate an alarm by closing
or opening a circuit on the happening of either one, or both1 of two events--
when the rate of rise of the temperature of the ambient atmosphere exceeds a
predetermined prescribed standard, for example, the 15F per minute standard
set by Underwriter Laboratories of Canada and Underwriter Laboratories Inc. of
1~ the United States, and/or when the ambient temperature exceeds a predetermined
fixed temperature.
These detectors must also operate in all environmental conditions,
for example, extremes of humidity, variations of heat and cold, and acidic or
alkaline vapour mediums.
The necessity for such operation has been recognized by various
Governmental and independent examining bodies, and standards have been set
which the devices must meet or exceed. One such body is the Fire Insurers'
Research and Testing Organization (FIRTO for short) of the United Kingdom,
who as part of its testing program, has prescribed that such fire detectors
must pass a sulphuric acid environment test. This test requires that the fire
detector sit in a sulphuric acid environment for a predetermined time and
thereafter, still be operable. However, no fire detector that vents to the
atmosphere tested with the rate of rise ~eature has remained operable after the
time period spent in the sulphuric acid vapour medium. The reason lies in the
construction of the vented detector incorporating the rate of rise feature. The
chamber between the shell and the diaphragm and diaphragm and base must be vented
to atmosphere to permit normal atmospheric expansion due to temperature
fluctuations without actuating the alarm.
The vent apertures if left unprotected in the acidic environment,
permit the acidic environment to be drawn into the chambers when the detector
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1 is breathing during normal temperature fluctuations, corroding the electrical
contacts.
Surrounding the vents with a wall and covering the wall created with
a closure gap, providing a small vent hole in the cap wall or between the cap
and wall only accentuates the problems of corrosion. The small vent hole, it is
thought, acts as a pump drawing in and exhausting substantial amounts of aci~ic
vapour through the small vent hole and permits condensation of the vapour,
thereby trapping the liquid acid in the contact area.
Additionally, during the tests, some heat collecting fins on certain
fire detectors were also attacked by the corrosive vapour and lost their
temperature sensitivity due to the formation of a residue on the fin as a
result of the reaction between the metal fin and fusible link (if exposed--
holding the plunger), and the sulphuric acid vapour.
Where the fin and ferrule were combined in one piece, in the detector,
the fin was not only attacked by the vapour, but the fin could not be manu-
factured of a large diameter at reasonable cost. However, it is desirable to
manufacture fins of large diameter for enhanced terperature sensitivity. Where
attempts have been made to make the fin-ferrule combination from two components,with the fin of large diameter, the union has not yielded a satisfactory
result. Particu1arly, where the two pieces are to be joined, they must be
"married" to effect maximum metal contact at the joint for effective heat
transfer between the components, to the fusible link.
It is therefore, an object of this invention to provide an improved
fire detector and structural compoents useful therefor.
It is a further object of this invention to provide an improved fire
detector vented to atmosphere having a rate of rise feature suitable for use
in an acidic vapour medium.
It is a further object of the invention to provide an improved
detector having an improved heat fin for the collection and effective transfer
of heat to the fusible link holding the plunger for release at a fixed pre-
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1 determined temperature (the fusion temperature of the fusible link).
Further and other objects of the invention will be realized bythose skilled in the art from the following summary of the invention and
detailed description of Dreferred embodiments thereof.
SUMMARY OF THE INVENTIO,J
Unexpectedly, according to one aspect of the invention, an improved
fire detector vented to atmosphere, capable of closing an alarm circuit
when the rate of rise of the temperature of the ambient atmosphere exceeds
a predetermined prescribed rate of rise of temperature is provided comprising
a base supporting a diaphragm enclosing a space between the base and
diaphragm, a shell secured to the base enclosing a space between the
diaphragm and shell, electrical circuit contacts mounted on the base for
being closed when the actual rate of rise of the temperature of the
atmosphere in the space between the diaphragm and shell exceeds a
predetermined rate of rise of temperature, vent aDertures through the
base from the spaces between the diaphragm and shell and between the
diaphragm and base to the back of the detector, the irprovement comprising
the vent apertures each being surrounded by an endless wall covered by a
closure caD having a top and depending skirt, small projections disposed
between the top of the closure cap and the top of the endless wall and
thin posts or lugs between the endless wall and depending skirt for
spacing the top of the wall from the top of the closure cap and spacing
the endless wall from the depending skirt, (preferably the wall including
the relatively small projections on the top and the relatively thin posts
or lugs extending from the side to enable the closure cap to seat on the
small projections on the top of ~he skirt of ~he closure cap against the
outer surface of the posts or lu9s), to cover the vent aperture permitting
the spaces between the diaphragm and base and shell and base to be vented
to atmosphere under normal expansion and contraction of the ambient atmosphere
in the fire detector without drawing amounts of air from outside the
cover and wall into the volume between the cover and the wall.
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l According to another aspect of the invention, the projections on the
top of the wall may number at least three, and the posts or lugs may number at
least three;
According to another aspect of the invention, the projections on the
top of the wall may extend about 1/32" (about 8/10 mm.) above the top of the
wall;
According to another apsect of the invention, the posts or lugs may
project about 40/1000" (about lmm.) from the wall and may be about 3/32"
(about 2 4/10 mm.) wide,
According to another aspect of the invention, an improved fire
detector is provided having claim actuating means for actuating an alarm at a
predetermined temperature and a fin for collecting heat from the ambient atmos-
phere, the improvement comprising the fin being connected by a ferrule to alarm
actuating means for actuating an alarm at a predetermined temperature, the
connection between the fin and the ferrule having been formed by causing metal
in an end portion of the ferrule flow over the fin metal surrounding the aper-
ture of the fin through which aperture the ferrule extends to provide a thin
layer of ferrule metal over fin metal.
This connection is accomplished by choosing a ferrule of a con-
figuration according to the method of union of the ferrule and fin to precludethe ferrule from collapsing under the forces applied by such method to cause the
ferrule metal to flow radially to form the union between the fin and ferrule.
For example, where a blind hole ferrule having a closed end is to be secured
to a fin by the wobble method-the end of a riveting peen rotates around a
circle at for example, the approximate rate of 1000 r.p.m. on the face of the
end of the ferrule to cause ferrule metal to flow radially outwardly over the
fin metal adjacent the central aperture of the fin according to a circular path
around the centre of the ferrule-the ferrule has a concave face supported benindand by a mandrel in the blind hole to resist collapsing while the metal in the
concave face flows radially over the fin. Similarly, when using a punch press or
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1 vertical press the face of the blind hole ferrule is concave. Where the
ferrule is open holed, the ferrule is supported (including a mandrel positioned
in the open hole) and may be cold swaged and caused to flow radially over fin
metal to join the two employing the above methods. Preferably, this connection
of a blind hole, or open hole ferrule, to a fin is accomplished by a rolling
action of a riveting peen in a cycloidal motion (describing a series of loops
that overlap tangentially at the centre to give overall a rosette pattern)
against the end portion of the supported ferrule to cause such metal to flow
outwardly to intimately engage the fin metal adjacent the aperture. The
13 BRACKER RADIAL (t.m.) Riveting Machine, Models RN002, RN2119 and RN311 manu-factured by Bracker A.G., CH8330 Pfaffiken-Zurich, Switzerland, actuates the
riveting peen to describe the said motion in rolling the metal of the ferrule
into intimate contact with the fin metal adjacent the center aperture. Par-
ticularly, the very light axial force exerted by the machine on the peen and
rolling action of the peen, causes the metal to flow mainly in the radial
direction, virtually freeing the ferrule from stress;
As a result, the metal of the ferrule is married to the metal of the
fin. In this way, an anodized aluminum fin of relatively large diameter (and
thus nonsolderable, but immune to sulphuric acid) may be intimately connected
to a solderable blind hole tin plated aluminum ferrule which in turn holds the
fusible link of a detente in the blind hole out of contact with the ambient
atmsophere. Therefore, the resultant detector is unaffected by a sulphuric acid
vapour environment;
According to another aspect of the invention, the fin may be
corrugated to agitate the air passing over the fin causing turbulence thereby
presenting more heated ambient air in contact with the fin, for more effective
heat transfer;
For rolling the ferrule with the open hole to the fin, stepped or
riveting peen having a flat central portion of substantially the same inner
diameter as the aperture in the ferrule extends into the hole of the ferrule and
1 includes flat side portions stepped from the flat central portion for engaging
the end portions of the ferrule to be rolled;
In the case of the ferrule with the blind hole, the tool is flat and
is greater in diameter than the ferrule, to roll the ferrule adjacent the blind
hole into intimate contact with the fin material;
The invention will now be illustrated with reference to the following
drawings of preferred embodiments of the invention, and detailed descriptions
thereof.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a perspective view of a fire detector operating to actuate
an alarm, when the rate of rise of the temperature of the ambient air exceeds a
predetermined prescribed rate and, when the ambient temperature exceeds a
predetermined fixed temperature, according to a preferred embodiment of the
invention;
Figure 2 is a top perspective view of the detector of Figure 1 partly
cut away;
Figure 3 is an exploded view of part of the detector shown in Figures
1 and 2;
Figure 4 is a vertical cross-sectional view of the detector shown in
Figures 1, 2 and 3;
Figure 5 is an exploded view of part of the structure shown in Figures
2 and 4;
Figure 6 is a cross-sectional view taken along the line 6-6 of Figure
5 with the closure cap secured looking in the direction of the arrows;
Figure 7 is a cross-sectional view of the fin component of the
detector shown in Figure 2;
Figure 8 is an exploded view of component parts of the detector of
Figures 2 and 4;
Figure 9 is a perspective view of a ~errule having an aperture there-
through for use in another embodiment of the invention;
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1 Figure 10 is a perspective view of a Bracker Radial Riveting Machine
Model RN002 for use according to the preferred embodiments of the invention;
Figure 11 is a schematic illustrating part of the operation of the
machine shown in Figure 10;
Figures 12 to 15 inclusive are cross-sectional views of the creation
of the joint between a blind hole ferrule and fin according to the first pre-
ferred embodiment of the invention shown in at least Figures 1, 2, 3 and 4;
Figure 16 (found with Figure 10) is a schematic cross-sectional side
view of the joint created by carrying out the operation shown in Figures 12 to
15 inclusive;
Figures 17 and 18 are cross-sectional views of the creation of the
joint between an open ferrule shown in Figure 9 and fin according to a second
embodiment of the invention;
Figure 19 (found with Figure 10) is a schematic cross-sectional side
view of the joint created by carrying out the operation shown in Figures 17 and
18;
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF T~E INVENTION
With reference to Figure 1, there is shown a fire detector 20, com-
prising base 22, and outer cup-shaped shell 24 carrying annular heat collecting
fin 26. Both shell 24 and fin 26 are made of anodized aluminum. Fin 26 is also
corrugated having spaced concentric annular ridges 28 (See Figures 16 and 19).
Fin 26 is positioned with respect to shell 24 by tin plated aluminum ferrule 30
extending through central aperture (not shown) in the center of shell 24.
Ferrule 30 supports detente member 32 (see Figures 3 and 4) in blind bore 34 of
ferrule 30 by fusible link 36 which fuses at a predetermined temperature.
Detente member 32 supports tapered compression spring 38, tapering in a
direction away from fin 26, for being compressed by flange 40 of detente
member 32 when assembled in shell 24. The other end of compression spring 38
rests on gasket 42 sitting on shell 24;
Diaphragm 44 (See Figures 3 and 4) is stretched over annular wall 46
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1 into trough 48 in base 22 and held therein by a gasket 49 (sealed therein by
epoxy) for dividing the space between the shell 24 and base 22 into two
compartments SO and 52. Compartment 52 houses contacts 54 comprising stationary
contact point 56 on the end of contact screw 57 supported by conical spring 57,
and contact spring 58. Calibrated vent 60 (employing bushing screw 62 for
calibration) from compartment 50 to the back of base 22 permits predetermined
amounts of air to pass therethrough under normal conditions of expansion and
contraction of the air within compartment 5~. Compartment 52 vents through
aperture 64 surrounding contact screw 57. On the other side of base 22 are
electrical contact screws 66 and 68~ and opening 70 for vent 60 surrounded by
annular wall 74. Central annular wall 82 surrounds aperture 64. Each of
apertures 60 and 64 are covered by closure caps 86 best shown in Figures 5 and
6. Particularly, spacer projections 88, 1/32" (about 8/10 mm.) high are disposedon the top of annular walls 74 and 82 on which the caps seat respectively. Each
cap 86 is slightly larger by the width of two side Projections 90 (3/32" (about
2 4/lO mm.) wide and 40/1000" (about 1 mm.) deep) to secure the cap over each
projection to cover each well but to permit communication of the well with the
ambient air without drawing amounts of air from outside cover 86 and walls 74
and 82 into the volumes between the respective covers and walls.
With reference to Figure 7, fin 26 is married to blind hole tin
plated aluminum ferrule 30 and is used to secure detente member 32 shown in
Figure 8. Because the ferrule is tin plated aluminum, it can be fused to the
fusible link 36 of de~ente member 32. Fin 26 and ferrule 30 are married by the
Bracker Radial Riveting Machine RN002 as shown in Figure 10 supporting riveting
peen 92 for marrying fin 26 and ferrule 30 as shown in Figure 13, 14 and 15 by
a rolling action applled by flat face riveting peen 92 to the end of ferrule
30 to describe a series of loaps that overlap tangentially at the center to
give overall, a rosette pattern (See Figure 11). Therefore, most of the force
exerted by peen 92 is a rolling action (minimal axial force) causing the
ferrule material to flow mainly in a radial direction (See Figures 13, 14 and 15)
providing a rivet head substantially free from stress, and marrying the metals
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1 together. While not shwon, ferrule 30 and fin 26 are supported against movement
by a rigid support under or behind the area in contact with peen 92. The
resultant union is shown in Figure 16.
Figure 9 illustrates an open hole ferrule 281 having aperture 28
S therethrough and Figures 17, 18 and 19 illustrate the method of union. Once
again fin 26 and ferrule 281 are rigidly supported including the use of a
mandrel inside open hole ferrule 281. However, riveting peen 92 has a flat
central portion 94 for projecting into aperture 2811 with ring annular stepped
portion 96 spaced from, and surrounding, central portion 94 for rolling over
top edge 98 of ferrule 281 by the same motion to marry fin 26 to ferrule 2&1 as
shown in Figure 19.
As many changes could be made to the invention without departing
from the scope thereof, it is intended that all matter contained herein be
interpreted as illustrative thereof and not in a limiting sense.
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